326 Albert V. James.- 



valley. This also has the effect of sharpening the spur, and the- 

 placing of the flood plain,, not at the end of the spur, but on the 

 down-valley side of it. (2a.) 



Meander Belt. — In youthful streams, such as Deep Creek, the 

 belt of wandering and the meander belt coincide with one another. 

 The stream by lateral swinging widens its meander belt, but this 

 tendency is checked by (a) the down-valley sw^eep of the meanders 

 (Avliich would eventually cut through the spurs), and by (b) the 

 formation of new channels at flood time across low spurs. 



Relation hetwetn Radius of Meander and Volume of Water. — 

 W. M. Davis has shown (2a and 9), that the radius of a meander, 

 Avhere slope and load are equal, is proportional to the volume of 

 Avater. This is exemplified in Jackson's Creek, Deep Creek and the 

 Maribyrnong River. Jackson's Creek has a slightly smaller 

 volume than Deep Creek, and the radii of its meanders are slightly 

 smaller than those of Deep Creek. Similarly the radii of the Mari- 

 byrnong meanders are considerably larger than those of the- 

 creeks. 



Hanging Valleys. — Excellent examples of hanging valleys are 

 found along both Jackson's Creek and Deep Creek. In every case 

 these tributary streams flow only after heavy rain. The best 

 example is that to the south-west of the main granodiorite out- 

 crop. This small stream has been formed/ along the junction of 

 the basalt, and the granodiorite. At its junction with' Deep Creek 

 there is a fall 80 ft. in height. Owing to their poor supply of 

 water the tributary streams are unable to corrode their beds as 

 rapidly as the main streams. This is the chief cause of the lack 

 of adjustment between the tributaries and the main streams in 

 this area. At Hanging Valley (see Z, Plate XXXII.), this lack of 

 adjustment is increased by the hard compact hornfels in its low^er 

 course. 



Deserted Bed of Jackson's Creek. — An old accumulation of 

 boulders can be seen in the right bank of the Maribyrnong River, 

 a quarter of a mile south of the junction of the creeks. Some of 

 the boulders are huge, some small, some of basalt, some of con- 

 glomerate, and othei-s of sandstone, but none of granodiorite. 

 It was the old bed of Jackson's Creek which deserted it when it 

 flowed 6 ft. above its present level. If Deep Creek had contri- 

 buted boulders to the conglomerate, granodiorite also would have- 

 been represented. 



